This application is for a Research Scientist Development Award, Level I. The application describes a comprehensive program of training and research in the field of obesity and weight regulation. The proposed training in the areas of 1) regulation of food intake and body weight, 2) energy expenditure and clinical nutrition, and 3) body composition will contribute significantly to my scientific development and enable me to complete the proposed research more successfully. The research proposed in this application will examine three primary issues: 1) the long-term treatment of obesity in adults by very-low-calorie diet and behavior therapy; 2) the treatment of obesity in black adolescent females; and 3) the prevention of obesity in young children through a school-based intervention. The study on the treatment of obese adults will examine resting energy expenditure and body composition to determine if they are adversely affected by very-low-calorie diet (420 kcal/day). In particular, we will determine whether the prolonged use of a very-low-calorie diet reduces energy expenditure and lean body mass in a fashion that renders maintenance of weight loss more difficult. Changes in body composition will also be examined in the teenagers in the second study. It is important to demonstrate that youngsters do not lose vital lean body mass will dieting. This is the first major study of the treatment of obesity in black children. The school-based program for the prevention of obesity continues a line of investigation that our research team has been pursuing for the past several years.